1. Field of the Invention
The present invention relates to coating compositions, and more particularly but not by way of limitation, to coating compositions which, when cured, provide substantially transparent coatings having enhanced abrasion resistance. In one aspect, the present invention relates to a coating composition having improved stability wherein the coating compositions are derived from aqueous-organic solvent mixtures containing effective amounts of epoxy functional silanes, tetrafunctional silanes and multifunctional compounds such as multifunctional carboxylic acids, multifunctional anhydrides, and mixtures thereof.
2. Description of Prior Art
The prior art is replete with compositions which, when applied to substrates and cured, provide transparent, abrasion resistant coatings for the substrates. Such coatings are especially useful for polymeric substrates where it is highly desirable to provide substrates with abrasion resistant surfaces, with the ultimate goal to provide abrasion resistant surfaces which are comparable to glass. While the compositions of the prior art have provided transparent coating compositions having improved abrasion resistant properties, such prior art compositions are generally lacking when compared to glass. Thus, a need has long existed for improved compositions having improved stability and which, when applied to a substrate, such as a polymeric substrate, and cured provide transparent, highly abrasion resistant coatings. It is to such compositions and processes by which such compositions are manufactured and applied to substrates that the present invention is directed.